Various types of spinal column disorders are known and include scoliosis (abnormal curvature of the spine), kyphosis (backward curvature of the spine), spondylolisthesis (forward displacement of a lumbar vertebra), and other disorders such as ruptured or slipped discs, broken or fractured vertebrae, and the like. Procedures to stabilize areas of the spine for both fusing spinal vertebrae together and for other stabilization purposes often require the use of a spinal tether. The existing spinal tethers, of which we are aware on the market, come in straight lengths or circular, xe2x80x9cloopxe2x80x9d geometries. These tethers typically rely on implants, anchors, or knots to secure the tether to the spine. Additionally, such implants are of fixed length requiring careful measurement of the distance around the anatomy to which the tether is secured or between the anchor points to which the tether is attached. Such precise measurement is difficult prior to surgery and, when done during surgery, results in longer operating times as measurements are taken and a spinal tether of the appropriate length is manufactured.
In one embodiment, the apparatus comprises an adjustable tether having a polymer strand with a first end and a second end and a first end portion and second end portion between the first end and the second end. The polymer strand has an intermediate portion between the end portions. The first end is secured in wrapped condition to form an eyelet in the first end portion. The eyelet has a first side and a second side and an aperture defined between the first side and the second side. The aperture has a cross-section such that the second end may pass therethrough in the direction from one of the sides to the other of the sides. The apparatus further includes a crimp with a bore defined therethrough. The intermediate portion of the tether extends through the bore. The crimp has a first portion with a cross-section such that the first portion will not pass through the aperture. The crimp has a first state and a second state, the first state permitting the polymer strand to move within the bore, the second state locking the intermediate portion within the bore wherein the intermediate portion is received in the bore only once.
In another embodiment, the apparatus comprises an adjustable tether having a polymer strand with a first part and a second part, each of the parts between a first end portion and a second end portion. The first part is closer to the first end portion than the second part. The first end portion is wrapped around and contacts the first part to form an eyelet with a first side and a second side. The apparatus has attachment means for holding the first end portion in contact with the first part. The eyelet has an aperture defined between the first side and the second side, the aperture having a cross-section such that the second end may pass therethrough. The second end portion passes through the aperture in the direction from the first side to the second side to form a loop with a length and the apparatus has means for fixing the length of the loop.
In another embodiment, the apparatus comprises a grommet with a top surface and a bottom surface and interior and exterior side surfaces extending between the top surface and the bottom surface. The interior side surface defines an aperture between the top surface and the bottom surface. The apparatus also includes an artificial strand having a first end portion and a second end portion. The first end portion is attached to the grommet and the second end portion passes through the aperture in a direction from the bottom surface to the top surface to form a loop. The apparatus further includes a crimp with a bore defined therethrough, the second end portion passing through the bore. The crimp has a first portion with a cross-section such that the first portion of the crimp will not pass through the aperture. The crimp has a first state and a second state. The first state permits the artificial strand to move within the bore, the second state locks a portion of the artificial strand within the bore.
In yet another embodiment the apparatus comprises a grommet with a top surface and a bottom surface and interior and exterior side surfaces extending between the top surface and the bottom surface. The interior side surface defines an aperture between the top surface and the bottom surface. The apparatus also includes an artificial strand with a first end portion and a second end portion and means for attaching the first end portion to the grommet. The second end portion passes through the aperture in a direction from the bottom surface to the top surface to form a loop.